Page 116 - ICSE Chemistry 8

5. A _____________ equa on has an equal number of atoms of one or more elements in the reactants
and products.
6. Decomposi on of water into hydrogen and oxygen occurs in the presence of _____________.

B. Iden fy the error in the given statements. Circle the incorrect word and write the correct word in
the blank.
1. Symbols of most of the elements are denoted by the second le er of
the name of the element. __________________
2. The innermost shell of an element is called the valence shell. __________________

3. A compound is a charged par cle which is formed when an atom or
a group of atoms gains or loses electrons. __________________

4. A molecule of a compound is represented using a symbol. __________________
5. A ca on is a substance that alters the rate of a chemical reac on without
itself undergoing any change. __________________
6. Some chemical reac ons proceed in both the direc ons and are called
double reac ons. __________________

C. Write the symbols of the following elements.

Element Symbol Element Symbol
Carbon Nitrogen
Phosphorus Sulphur

Aluminium Calcium
Germanium Magnesium

Pla num Zinc

D. Write the symbols of the following ions.

Ion Symbol Ion Symbol
Calcium ion Cupric ion
Magnesium ion Sodium ion

Zinc ion Bromide
Fluoride Sulphide

E. Match the columns.

Radical Chemical formula
1. Ammonium (a) (NO ) –
2
2. Hydrogen carbonate (b) (SO ) 2–
4
3. Nitrite (c) (HSO ) –
3
4. Sulphate (d) (Cr O ) 2–
7
2
5. Bisulphite (e) (NH ) +
4
6. Dichromate (f) (HCO ) –
3

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